RED donation quantity edit validation system test

When edited donation amount plus available inventory is less than requested
inventory for distribution, it should redirect to the edit donation page,
display an error, the original donated item name, and the original amount

spec/system/donation_system_spec.rb

@@ -561,13 +561,13 @@
 
     context "When editing an existing donation" do
       before do
-        item = create(:item, organization: organization, name: "Rare Candy")
-        create(:storage_location, organization: organization)
+        @item = create(:item, organization: organization, name: "Rare Candy")
+        @storage_location = create(:storage_location, organization: organization)
         create(:donation_site, organization: organization)
         create(:product_drive, organization: organization)
         create(:product_drive_participant, organization: organization)
         create(:manufacturer, organization: organization)
-        create(:donation, :with_items, item: item, organization: organization)
+        create(:donation, :with_items, item: @item, organization: organization, storage_location: @storage_location)
         organization.reload
         visit donations_path
       end
@@ -599,6 +599,29 @@
         expect(donation.money_raised).to eq(10002)
       end
 
+      # Bug fix - Issue #4172
+      context "when donated items are distributed to less than donated amount " \
+        "and you edit the donation to less than distributed amount" do
+        it "shows a warning and displays original names and amounts" do
+          partner = create(:partner)
+          visit new_distribution_path
+          select partner.name, from: "Partner"
+          select @storage_location.name, from: "From storage location"
+          fill_in "distribution_line_items_attributes_0_quantity", with: "99"
+          click_button "Save"
+          click_button "Yes, it's correct"
+
+          visit donations_path
+          click_on "View"
+          click_on "Make a correction"
+          fill_in "donation_line_items_attributes_0_quantity", with: "1"
+          click_on "Save"
+
+          expect(page).to have_content("Error updating donation: Requested items exceed the available inventory")
+          expect(page).to have_xpath("//select[@id='donation_line_items_attributes_0_item_id']", text: @item.name)
+        end
+      end
+
       it "Does not default a selection if item lookup fails" do
         total_quantity = find("#donation_quantity").text
         expect(total_quantity).to_not eq "0"